i) Field of the Invention:
The present invention relates to a level meter used for audio systems or the like and a display control device for use in display control of the level meter.
ii) Description of the Related Arts:
Conventionally, a level meter composed of an LED (light emitting diode) array, a liquid crystal or the like is used in audio systems, such as a CD (compact disc), or a DAT (digital audio tape), video systems such as a TV, or a VTR (video tape recorder), or a tachometer of an automobile or the like. In the level meter of this kind, a so-called peak hold display is performed.
The peak hold display functions, for example, not only to display a level of an audio signal but also to hold its peak value for a predetermined time and to display the peak value at the same time. In a level meter of an audio system, as shown in FIG. 4, there are a plurality of frequency component displays (spectrum analyzer displays) 10-1 to 10-6 of 50 Hz, 100 Hz, 330 Hz, 1 kHz, 3.3 kHz and 10 kHz bands and one level display 10-7 of the audio signal. In this case, a peak hold display 10-8 is executed in the level display 10-7. Of course, the peak hold display can be carried out in the spectrum analyzer displays 10-1 to 10-6.
In FIG. 5, there is shown a display control device, as disclosed in Applicant's copending Japanese Patent Application No. Hei 3-160356. In this case, an analog audio signal is input to a display control IC 12 via a BPF (band-pass filter) 14. The BPF 14 performs band-pass filtering of the audio signal to output analog frequency components f1 to f6 for the spectrum analyzer displays. The BPF 14 also outputs a signal LEV representing an average level of the frequency components f1 to f6.
The display control IC 12 includes two A/D converters 16 and 18, a display controller 20 and a memory 22. The A/D converter 16 converts the output signals of the BPF 14 into digital audio signals. The digital audio signals output from the A/D converter 16 are input to the display controller 20, and a level and spectrum analyzer display and a peak hold display are executed in an LCD 24 as a display means, as shown in FIG. 4.
The memory 22 is used for storing a recovery time input to the display controller 20 via the A/D converter 18, and the like. That is, in order to readily see the display on the LCD 24, the memory 22 is used for performing a recovery control for showing the variation of the actual audio signals as a gentle variation with a predetermined time constant. The recovery time represents the time constant in the recovery control.
However, in the above-described conventional display control device, the time for holding the peak value is fixed and thus a setup change of the time depending on the tastes and functions of users can not be carried out. Hence, the same peak hold time must be accepted when listening to, for example, a rock and roll number and a popular ballad number and the user's satisfaction is impaired.